With difficulty of 1024, hashrate will fluctuate more, however, if nothing is showing up then something is wrong, most likely on your end. It makes no sense to "rob" people with 1 rig when there are quite a few with 20+ MH/s who you could take 5-10% potentially from without them noticing (which would add up to what he is supposedly "taking" from you).

More likely is your computers are infected and the mining is being redirected to a different address, or your configs are wrong. If this was a widespread issue, the people who are normally making $500+ a day would be livid on here.

Unfortunately, with the size of the pool right now, I doubt H2O will respond to you individually... he's busy enough keeping the ship above water with regards to the DB I/O issues. In fact, having a few less miners would appeal to most of the bigger players here